Bowl mill with vane means providing uniform velocity upwardly swirling air currents



BOWL MILL WITH VANE MEANS PROVIDING UNIF ORM VELOCITY UPWARDLY SWIRLINGAIRCURRENTS Filed Aug. 25, 1944 3 Sheets-Sheet 1' D.2, 1947.. G. H.FRANGQUIST K 9 2,431,746

n b A e.-H. FRANGQUIsT 2,431,746 BOWL MILL WITH VANE MEANS PROVIDINGUNIFORM Dec; 2, 1%7.

VELOCITY UPWARDLY- SWIRLIN G AIR CURRENTS Filed Aug. 25, 1944 5Sheets-Sheet 2 Dec. 2, 1947. H. FRANGQUI 2, ,7 BOWL MILL W VANE MEANSPRO ING UNIFORM VELOCITY UPWARDLY SWIRLING AIR CURRENT-S Filed Aug. 25,1944 3 Sheets-Sheet 3 mp. U l

I 1 I I v/ I, I IN "MI! I It i v v Patented Dec. 2, 1947 FFICE BDWL MILLWITH VANE MEANS PROVIDING UNIFORM VELOCITY UPWARDLY SWIRL- ING AIRCURRENTS Gustav H. Frangquist, Chicago, Ill., assignor to CombustionEngineering Company, Inc., New York, N. Y., a corporation of DelawareApplication August 25, 1944, Serial No. 551,130

4 Claims.

This invention relates to pulverizing apparatus and has for itsprincipal object the provision of a new and improved form andarrangement of parts whereby the air currents, utilized for carrying thepulverized material out of the apparatus, may be maintained at uniformvelocity at all locations within the apparatus whereby the material,when sufiiciently pulverized, will be discharged without unduesuspension and consequent circulation of the heavier particles ofmaterial in the air current.

The invention as herein illustrated is designed particularly for use inconnection with bowl mills, such as are illustrated in the Crites UnitedStates Patent No. 2,112,359, granted March 29, 1938, although theinvention is not to be restricted to use in connection with suchapparatus, except so far as the claims may be so limited.

In a pulverizing apparatus of the general class herein shown, acomparatively shallow bowl is given rotary movement about a verticalaxis within a closed casing or housing. Two or more rollers arerotatably mounted and extend into the bowl so as to have a crushingeffect on particles carried around on the upwardly and outwardlyinclined face of the bowl. The parts are arranged so that there is anannular opening between the outer wall of the bowl and the inner wall ofthe housing through which air introduced in the space below the bowlmoves upwardly so as to pick up and float away pulverized materialforced over the edge of the bowl.

One object of the invention is to provide an improved arrangementwhereby the air introduced into the housing will be so distributed aboutthe periphery of the bowl as to avoid the formation of high and lowvelocity zones in the air and thereby prevent substantial quantities ofinsufficiently pulverized material from being suspended in the highervelocity air zones and carried upwardly through the apparatus. Thisresult has been accomplished in the preferred construction by the use ofan arrangement comprising a series of vanes in spaced relation to eachother about the bowl, such vanes being in substantially radial positionbut disposed obliquely at a suitable angle from the horizontal, with theupper ends of the vanes in the lead with respect to the direction ofrotation of the bowl. The size of the annular opening between the bowland the wall of the casing or housing is such with respect to the sizeof the stream of air introduced into the housing that the distributionof the air about the entire periphery of the bowl is assured, and theangular positions of the chute 22.

vanes insure that the several portions of the stream of air betweensuccessive vanes shall be directed forwardly and upwardly with respectto the direction of rotation of the bowl and that oversized material,finding entrance between the vanes will be deflected upwardly therebyand carried in the air stream back into the bowl of the mill.

Another object of the invention is to include the provision of theimproved constructions and arrangements herein shown and described inconnection with one approved form of apparatus.

Fig. 1 is a central vertical sectional view through one preferred formof bowl mill, showing the improvement of the present inventionincorporated therein.

Fig. 2 is a horizontal sectional view taken substantially at the line 22of Fig. 1.

Fig. 3 is a perspective view of a fragmentary portion of .a horizontalplate mounted at the upper face of a duct through which air is deliveredinto the apparatus, showing in position one of the vanes of that portionof the series of vanes.

Fig. 4 is a perspective view of the vane structure of Fig. 3.

Fig, 5 is an enlarged detail view substantially similar to a portion ofFig. 2, being substantially a horizontal sectional view taken at theline 55 of Fig. 6, and

Fig. 6 is a vertical sectional View taken substantially at the line 6-6of Fig. 5.

Referring now to the several figures of the drawings, in whichcorresponding parts are in dicated by the same reference characters, ISindicates a base plate suitably secured in position, upon which ahousing or casing I6 is fixedly mounted. Within the housing l6, a bowlI! of approved type is rotatably mounted so as to be driven through themedium of a vertical shaft i8 which in turn is driven by suitabledriving mechanism in the gear housing I9 below the base plate I5 so asto cause the bowl to rotate in clockwise direction in Fig. 2.

In the arrangement shown, the bowl I! is provided with a grinding ring20, with which three rollers 2| cooperate for crushing and pulverizingmaterial fed into the bowl through a Each of the rollers 2| is rotatablymounted in position by means comprising a sleeve assembly 22 engagingthe roller and freely rotatable on a shaft 23. The shaft is fixed in anouter sleeve 24 which is pivotally mounted on a horizontal axis at 25.An arm 26 fixedly mounted on the sleeve 24 has an effective bearing onthe upper end of a coiled spring 21, the lower end of which bearsagainst a bracket 28 held rigidly in position with respect to thehousing IS. The arrangement is such that the springs 21 press therollers 2| yieldingly toward the grinding ring 20. As is best shown inFig. 1, each of the sleeves 24 extends upwardly through a suitableopening at the top face of the housing l6 into a deep inwardly pressedgroove 29 in the outer face of an extension casing member 30 securedabove the casing memb'er I6, means being provided preferably about thesleeves 24 for preventing the escape of air.

As is best shown in Fig. 1 ,'the bow-l I 1 is spaced a short distancefrom the inner face of the housing l6 so as to provide an annularopening between the bowl and the housing, the arrangement being suchthat a stream of air introduced either by suction or pressure into thehousing l6 below the bowl is caused to rise through the annular openingso as to pick up 'and'iloat away particles (if material which have beensufilcient'ly pulverized in the bowl of the mill and forced upwardly andoutwardly therefrom during the grinding operation. The suspendedparticles which are insufiiciently pulverized are deflected inwardly byangular deflectors Hie, secured to the inner wall of the housing, andthereby returned to the bowl I! for further reduction.

It is the principal object of the present invention to provide animproved arrangement by which a stream of air fed into the housing I6 iscaused to be distributed as desired about the periphery of the bowl, itbeing the object in many instances to make the distribution of the airsubstantially uniform throughout the entire circumference of the bowl.

The air rising through the annular opening between the bowl and thehousing passes upwardly along opposite sides of the inwardly pressedportions 29 of the housing and is carried upwardly along the upwardlyflared shell 3i, thence through a series of openings'32 through theupper edge portion of the shell 3!. The air is then deflected downwardlya short distance in order to gain access to the delivery pipe 33 throughwhich the air and the particles held suspended therein are dischargedfrom the apparatus, The force of the air is such as to hold insuspension particles of the material being pulverized which approximatea predetermined size and Weight. Any particles of material of excessivesize carried by the air stream above the deflectors W will be caused topass on downwardly when the direction of the air changes at the lowerend portion of the pipe 33, 'such oversize particles being d'eliveredthrough an opening at 34 through the shell 31 again into the bowl Idirectly below for further pulverizing action.

The means for causing the desired distribution of the air stream aboutthe periphery of the bowl I! will now be described. Preferably the sizeof the air stream fed into the housing 16 is such with relation to thesize of the annular opening between the bowl and the housing as to causenecessarily more or less distribution of the air about the bowl. The airis fed into the housing I6 through a duct 31. In the embodi ment shown,the said duct 31 is located at one side of the center of the chamber and'consequently causes the air to follow a circular path corresponding tothe direction of rotation of the bowl I! and to the general path oftravel of the material discharged from'the bowl.

As is best shown in Fig. 1, where a portion 75 neath' the bowl.

of the bowl l1 and grinding ring 20 are broken away for clearness ofillustration, a series of vanes 38 are fixedly mounted in the annularopenings between the inner face of the wall of the housing It and theouter face of the bowl. The saidvanes may be secured in position in anysuitable manner, for example, welded directly to the wall of thehousing. These vanes are in oblique position at an angle of about 45degrees from the horizontal, and are of such length as to overlapvertically, the upper ends of the vane's being in advance in thedirection of rotation of the bowl and in the direction of the rotationalmovement of the air stream. Thesaid vanes 38, as will be seen byinspection of -1, are "arranged in radial position, so as to divide theannular opening between the bowl and the wall of the housing [6 into aseries of sections between the successive vanes. The vanes 38 aremounted in spaced relation to each other as described about the entireperiphery of the bowl except for a short distance opposite to the duct31 where an alternative arrangement is provided. This alternativeconstruction includes an arrangement of varies for stratifying the airin the upper portion of duct 31 adjacent the annular passage surroundingthe bowl ll.

A baflle plate 39, having a height equal to the adjacent vanes 38, isprovided within the duct 31 for deflecting the entering #air, suchbaffle plate constituting in effect a portion of the wall of the housingl6 and having a plurality of vanes 38 mounted thereon.

Across the top face of the duct 31, a transversely positioned plate 40is provided, having its inner "edge curved in substantially concentricrelation to the periphery of the bowl. Secured to the bottom face of thetransverse plate Ml are a plurality of air stratifying plates 4! inoblique position at an angle of approximately degrees from thehorizontal and extending in substantially parallel relation with respectto each other and with respect to the duct 31-. These plates -41 carryvanes '42 corresponding in size and shape with the vanes 38., andextending like the vanes '38 into close proximity to the periphery' 'ofthe bowl I I. The vanes 12 are in radial position with respect to thebowl, and are obliquely disposed with each v-a'n'e at an angle of about45 'degrees from the horizontal. The arrangement is such that the vanes42 complete the series of vanes 38 so as to provide similarly function-.ing vanes about the entire periphery ofthe bo'wl.

With a stream of 'air entering the housing 16 through the duct 31,'andwith such stream or air moving in clockwise direction about the chamberof said housing 'I'B as seen in Fig, 2, such air finds its way readilybetween the vanes which are disposed "so as to receive the air with aminimum of change of direction. The arrangement is such that the air isdistributed quite evenly among the comparatively large number ofopenings between successive vanes, so as robe caused to rise close tothe periphery of the bowl in position to pick up pulverized particles asthey are forced upwardly and outwardly from the bowl.

The spaces between the several vanes 38 and between the several vanes4'2 are such 'as 'to perini t large pieces of waste material, forexample tram iron which may be present in the materialbeing pulverizedbut which is not readily pulverized by the rollers 2-3 to passdownwardly between adjacent vanes and into the'space be- This wastematerial is swept from the bottom of the chamber beneath the bowl H, bymeans of one or more scrapers 35, into a discharge chute 36. Theoversized particles of coal, or other material being pulverized, whichare relatively light in weight in relation to the trap iron wastematerial and which may find entrance in the spaces between the inclinedvanes will be blown upwardly into the bowl, the inclined vanes servingas deflectors which cooperate with the force of the air stream to returnsuch particles to the bowl of the mill. However, the heavier particlesof foreign material will pass downwardly between the vanes into thelower chamber of the casing.

By the use of the improved construction, an effective control of the aircurrent is assured so as to provide good results by the use of a minimumstrength of air current and so as to enable the use of the pulverizingapparatus to advantage for pulverizing coal for feed directly to afurnace. With the air moving under control smoothly along the faces ofthe walls or at a sharp angle with respect thereto rather than movingwith a high degree of turbulence directly toward the walls, theeffectiveness of the air current for carrying away the pulverizedparticles by a flotation effect is greatly increased, and the efficiencyof the apparatus is correspondingly increased.

While the form and arrangement of the parts as shown in the drawings andas above described are preferred, it is to be understood that theinvention is not to be limited to such arrangement except so far as theclaims may be so limited, changes being well made in the arrangementwithout departing from the spirit of the invention.

I claim:

1. A pulverizing apparatus, comprising in combination a housing, a bowlrotatably mounted in said housing with an annular opening between thebowl and the wall of the housing, means for rotating the bowl in saidhousing about a vertical axis, means operative in said bowl forpulverizing material fed to the bowl, a conduit for directing a streamof air into said housing in a path substantially tangent to the innerwall thereof'so as to move upwardly through said annular opening and atthe same time to move about the outer face of the bowl in the samedirection as that in which the bowl is rotating, and vanes extendingbelow the upper portion of said conduit and arranged in substantiallyradial position in said housing in spaced relation to each other at theinner face of the housing with their inner ends in close relation to theouter surface of the bowl so that the vanes divide the stream of airinto a plurality of sections between successive vanes for obtaining apredetermined distribution of the air about the bowl.

2. A pulverizing apparatus, comprising in combination a housing, a bowlrotatably mounted in said housing with an annular opening between thebowl and the wall of the housing, means operative in said bowl forpulverizing material fed to the bowl, means for rotating the bowl insaid housing about a vertical axis whereby the material pulverizedtherein is thrown outwardly therefrom and carried in a general circularpath adjacent the wall of the housing, a conduit for directing a streamof air into said housing in a path substantially tangent to the innerwall thereof so as to move upwardly through said annular opening and atthe same time to move about the outer face of the bowl in the samedirection as that in which the bowl and said discharged material ismoving, and vanes between said bowl and said housing arranged to extendbelow the upper portion of said conduit and in oblique position withtheir upper ends in advance with respect to the direction of rotation ofsaid bowl so as to function as deflectors for returning oversizeparticles of material to the bowl.

3. A pulverizing apparatus, comprising in combination a housing, a bowlrotatably mounted in said housing with an annular opening between thereceptacle and the wall of the housing means for rotating the bowl insaid housing about a vertical axis, means operative in said bowl forpulverizing a material fed to the bowl, a duct leading into said housingopposite to said bowl for the introduction of a stream of air into thehousing so as to rise through said annular opening, vanes mounted on theinner face of the housing in oblique position at a substantial angleextend below the upper limits of the duct and arranged in obliqueposition corresponding to the position of said first-named vanes andserving with said first-named vanes to complete a series of vanessubstantially about the periphery of the bowl.

4. A pulverizing apparatus, comprising in combination a housing, a bowlrotatably mounted in said housing with an annular opening between thebowl and the wall of the housing, means for rotating the bowl in saidhousing about a vertical axis, means operative in said bowl forpulverizing a material fed to the bowl, a duct leading into said housingopposite to said bowl for the introduction of a stream of air into thehousing so as to rise through said annular opening, vanes mounted on theinner face of the housing in oblique position at a substantial anglefrom the horizontal in spaced relation to each other about the majorportion of the housing, a transverse plate extending across the upperface portion of the duct adjacent to said bowl, a series of spaced apartsupporting plates depending from said transverse plate opposite to saidbowl, and vanes mounted on said supporting plates in oblique positioncorresponding to the position of said first-named vanes and serving withsaid firstnamed vanes to complete a series of vanes substantially aboutthe periphery of the bowl.

GUSTAV H. FRANGQUIST.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,955 960 Hersch Apr. 24, 19342,112,359 Crites Mar. 29, 1938 2,237,021 Wood Apr. 1, 1941 1,697,704Wood Jan. 1, 1929 1,806,980 Krentzberg May 26, 1931

